The metabolism of prostaglandins either results in their biological inactivation or in a conversion to another class of prostaglandins with somewhat different physiological properties. The objective of the proposed research is to study the enzymes cayalyzing the early steps in prostaglandin metabolism in the human placenta. The enzymes will be isolated and purified, their characteristics will be established and the mechanisms controlling their activity will be sought. BIBLIOGRAPHIC REFERENCES: Braithwaite, S. and Jarabak, J.: Studies on a 15-Hydroxyprostaglandin Dehydrogenase from Human Placenta: Purification and Partial Characterization. J. Biol. Chem. 250, 2315 (1975). Powell, W., Hammarstrom, S., Samuelsson, B., Miller, W., Sun, F., Fried, J., Lin, C., and Jarabak, J.: Interactions between Prostaglandin Analogues and a Receptor in Bovine Corpora Lutea. Eur. J. Biochem. 59, 271 (1975).